In fact, USA would be far stronger today if Germany and Japan won the war.
Why do you think that? I can give you a few reasons why it isn't true. Firstly, If Germany and Japan had won the war, our European allies and trading partners would have been even more completely crushed than they were in reality, which would have been a major blow to our economy. Secondly, in the aftermath of the war, America was one of the few industrialized countries that had not been ravaged by war. As a result, America experienced unprecedented economic growth. Thirdly, the war cemented America's position as a superpower. Fourthly, had Germany won, that would mean that it had defeated Russia, so the Cold War would have been waged against an increasingly deranged sociopath named Adolf Hitler. That would have ended in WWIII rather than a cold war.